Landforms in the Big Creel< watershed include both steep mountains and narrow valley bottoms. 

 These landforms include structural breaklands, stream breaklands and steep alpine glaciated lands on 

 slopes in excess of 60 percent. Glaciated lands, mountain slopes and ridges and valley bottoms are on 

 the gentle to moderately sloping portions of the watershed. 



Disturbances such as fire and timber harvest release nutrients from vegetation and organic debris on 

 the soil surface. Many of the nutrients end up stored in the soil where they can be used by plants. 

 Some nutrients find their way into streams and ultimately end up in Flathead Lake, which is a state 

 priority for nutrient reductions based upon the recently completed Nutrient Management Plan and Total 

 Maximum Daily Load for Flathead Lake. Montan a. The two primary nutrients of concern for Flathead 

 Lake are nitrogen and phosphorus. The potential nutrient contribution for each individual landform is 

 rated from low to high in the following landform descriptions. The nitrogen yield rating is based on the 

 natural level of nitrogen in the soil, soil permeability and precipitation rate. The phosphorus yield rating 

 is based on the natural level of phosphorus in the soil and the sediment hazard. 



Another important component of these landforms are sensitive soils. Sensitive soils have an excess of 

 water in the soil, usually on a seasonal basis, but in some cases year around. When sensitive soils are 

 in their natural undisturbed condition they act as temporary storage site for water, allowing it to slowly 

 move down slope until it reaches springs, wetlands or streams or into groundwater if the underlying 

 bedrock is permeable. 



When sensitive soils are disturbed by management activities such as road building or timber harvest 

 the water can seep out of the soil and onto the road, skid trail or landing where it moves quickly down 

 slope. Water that would have moved slowly to a stream through the soil profile is now quickly routed to 

 a stream. This efficient routing of water increases water yields and the risk of sediment. 



A general description of the landform groups and their associated attributes follows. The description 

 includes a discussion of the potential nutrient contribution associated with forest disturbances and the 

 sensitive soils within each landfonn group. Figure - 5 is a map of these general landform groups for Big 

 Creek. 



Valley Bottoms - (5031 acres, 8.6% of Big Creek) 



Valley bottoms occur low in the landscape and are composed of stream terraces, floodplains, glacial 

 outwash plains and outwash terraces. Parent materials are sands, silts, or gravels underlain by 

 siltstones, or glacial deposits. The dominant slopes have gradients of 2 to 20 percent. Steep slopes 

 occur at the front edge of some terraces. The primary soils are deep with extremely gravelly sand and 

 loam textures. The vegetation is a mosaic of deciduous forest, coniferous forest, and wet meadows or 

 shrubland. 



Streams in this map unit are typically perennial and are predominantly 3rd to 4th order. Streams in this 

 landform group are typically a C stream type, which are low gradient systems (<2%), with moderate to 

 high sinuosity and low to moderate confinement. They occupy broad valleys with wide flood plains 

 bordered by abandoned terraces of alluvial soils (rounded rocks and sand). They are characterized by 

 well defined meanders, point bars, and alternating riffles and pool sequences. The streambed 

 materials typically range from fine sand to small boulder in size, with gravel to cobble size materials 

 being predominant. Most C-type streams have moderately high to very high sensitivity to increases in 

 stream flow or changes in sediment loads. In an undisturbed state these streams would produce little 

 sediment, even during large flood events due to the well-vegetated floodplains and streambanks. 



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